JP2004135489A - Current detecting method for inverter, its current detecting circuit, its abnormality detecting method, abnormality detecting circuit, display device, information processor, testing method, and testing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily detect changes of a circuit current caused by abnormalities of electrical discharge or the like in a non-contact state with a current route regarding an inverter which converts DC input to AC output and supplies the AC output to a load such as an FL pipe. <P>SOLUTION: The inverter 2 converts the DC input into the AC output and supplies the AC output to the load (the FL pipe 4). The changes of the circuit current are detected through the medium of magnetic flux changes Δψ caused by the changes of the circuit current of the inverter generated due to the electrical discharge. For example, when the changes of the circuit current occur due to breaking of wire electrical discharge and ground fault electrical discharge generated in the current route including the load of the inverter 2, the magnetic flux changes occur between core gaps of circuit wirings 14, 16, 52, and 54 and a transformer (an inverter transformer 22). The changes of the circuit current are detected in a non-contact state with the circuit wiring and the transformer or the like through the medium of the magnetic flux changes. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inverter that supplies an AC output to various loads, such as a fluorescent tube for a backlight of a liquid crystal display device.In particular, the present invention relates to a change in circuit current caused by disconnection discharge of circuit wiring or close discharge between high and low voltage parts. The present invention relates to an inverter current detection method, a current detection circuit, an abnormality detection method, an abnormality detection circuit, a display device, an information processing device, a test method, and a test device of the inverter that detect a change in magnetic flux.
[0002]
In a liquid crystal display (LCD), a fluorescent tube (FL tube) is used as a backlight light source, and an inverter is used in the lighting device. This inverter employs a constant current circuit for brightness adjustment and the like, and the FL tube is driven by a constant current drive at a high voltage of about 1.5 kV and a low current of about several mA, for example. The current route including the FL tube to which the AC output is supplied from the inverter is a wiring section from the high-voltage side winding of the inverter transformer to the FL tube, and includes a winding of the inverter transformer, a conductor pattern on the printed wiring board, and a connector. Since the wires pass through a number of members such as wires, the wires are long, and the circuit wires are thin and easily deformed by external pressure. In mobile phones and notebook personal computers, the installation space of the FL tube lighting device is particularly small, and thin wires from the inverter to the FL tube are easily deformed by external pressure.
[0003]
When a disconnection occurs in such a current route of the inverter, the current is interrupted by the disconnection. However, since the current is a high voltage constant current, a voltage rise occurs in the current route of the FL tube when the disconnection occurs, and the disconnection occurs. There is a possibility that the discharge generated at the location continues and the current route is maintained. When the current route is maintained, the tube current flows and the lighting of the FL tube continues. Since the operation abnormality cannot be known from the lighting state, the discovery of the operation abnormality is delayed. Continuation of such an abnormal state is undesirable.
[0004]
Therefore, regarding inverters that supply AC output to various loads, such as fluorescent tubes for backlights of liquid crystal display devices, abnormalities such as disconnection discharge of circuit wiring, destructive discharge between high and low voltage parts, and ground fault discharge are detected and continued. There is a demand for technology development for avoiding and displaying signs.
[0005]
[Prior art]
Conventionally, the following prior art documents exist regarding a technique for detecting such an abnormal operation of the inverter and continuously avoiding the abnormal operation.
[0006]
[Patent Document 1]
JP-A-6-140173
[0007]
[Patent Document 2]
JP-A-11-121190
[0008]
[Patent Document 3]
JP-A-9-113546
[0009]
Patent Document 1 discloses, as a protection device for a discharge lamp lighting system, which avoids the inconvenience that the operation of a transistor inverter is maintained even when the discharge lamp is turned off in the event of an abnormality, and extracts the output of the inverter. The oscillation state is monitored by a monitor circuit, and an abnormality such as a short circuit in the discharge lamp is detected from the monitor pulse voltage. When an abnormality occurs, the operation of the inverter is stopped by stopping the supply of the DC voltage, and the discharge lamp is turned off. However, such a protection device requires a monitor circuit that extracts and monitors the inverter output, a microcomputer that determines whether the monitor pulse voltage is normal or abnormal, and has a complicated configuration, and the output of the inverter is externally provided. Since it is taken out, it is necessary for the inverter to take measures such as coping with changes in operating conditions.
[0010]
Patent Literature 2 discloses a discharge lamp lighting device, which is connected to a discharge lamp by focusing on the fact that the value of the high-frequency voltage decreases when a high-frequency voltage applied to the discharge lamp is discharged between the ground and a low-voltage portion. The high-frequency voltage is detected by a high-frequency voltage detection resistor, and the high-frequency voltage is rectified and converted into a DC voltage. When the level is abnormal, the operation of the discharge lamp lighting device is stopped. However, this discharge lamp lighting device requires a high-frequency voltage detection resistor directly connected to the discharge lamp, and determines the difference between a normal state and an abnormal state (during discharge) by a resistance voltage dividing circuit constituted by the high-frequency voltage detection resistor. Since the determination is made based on the voltage ratio, the threshold level of the switching transistor, or the like, the accuracy of determining whether the operation is abnormal or normal is low, and the operation may be stopped due to the level change in the normal state. Also in this discharge lamp lighting device, since a high-frequency voltage detection resistor is connected to the high-voltage section to detect a high-frequency voltage, special measures are required for extracting the detected voltage, such as a change in circuit conditions.
[0011]
Patent Document 3 discloses that an overcurrent detection circuit uses a current transformer that detects a current supplied from a switching power supply unit to a load. This overcurrent detection circuit has a configuration in which a switching power supply is controlled by an overcurrent detection signal generated by detecting an overcurrent flowing through a load, and a DC output voltage is dropped from the switching power supply to the load. This does not detect a change in the circuit current due to a current route or a discharge generated on the load side.
[0012]
[Problems to be solved by the invention]
By the way, when a discharge is generated between a broken portion of a circuit wiring and a high / low voltage portion, it is possible to check an electrical change caused by the discharge. When a discharge occurs at the disconnection point, the voltage and current representing the discharge increase inside the inverter, but the amount of change is small, and even if the detected voltage is simply compared with the reference voltage, it is normal and abnormal. When the level difference from the time is small, a malfunction easily occurs, which is not practical. In order to enhance the detection accuracy of disconnection discharge and dielectric breakdown discharge between high and low voltage parts, a circuit combining a differentiating circuit and a timer circuit is necessary. However, such a circuit is complicated, and such a circuit is required for an inverter. The addition of is costly and is not practical. In addition, when the amount of waveform change between normal operation and discharge is small, as in the case of micro-discharge, even if a differentiating circuit is used, sufficient detection accuracy cannot be obtained, and malfunctions are liable to occur. Chip.
[0013]
When driving a load such as an FL tube using an inverter, disconnection discharges occurring in the current route and discharges between high and low voltage parts are found, and the continuation of abnormal conditions is prevented by the reliability of operation of the inverter and its load side. However, such a problem is not disclosed in Patent Literatures 1 to 3, and no solution is presented.
[0014]
Further, the failure due to the minute discharge of the LCD is a failure due to the assembling work of the LCD. The failure is detected by visual confirmation or the like, and the reliability and reliability of the detection are low.
Most of the ground fault discharges generated between the high voltage part and the surrounding ground are caused by scratches generated on the coating of the high voltage wiring, bites between the wiring members, breakage of the insulating tube of the soldered part, etc. In some cases, stress is applied to the semiconductor. For this reason, an additional test of the dielectric strength is required. In addition, the disconnection discharge of the high-voltage current route is caused by disconnection of a soldered portion, poor contact of a connector, disconnection of a wiring, and the like, and an electrical detection method of such a discharge is based on observation of a current waveform. Preparation of test equipment and test time are long. In the inspection, visual confirmation of the appearance is also performed. It is difficult to detect smoke disturbances that occur after a lapse of time even in products subjected to such tests. For this reason, there has been a demand for a test method and a test apparatus that can easily detect a fault such as a disconnection discharge or a ground fault discharge and obtain a highly reliable test result in an LCD.
[0015]
Therefore, the present invention relates to an inverter that converts a DC input into an AC output and supplies the AC output to a load such as an FL tube, and easily detects a change in circuit current due to an abnormality such as discharge in a current route without contact. The purpose is to:
[0016]
Another object of the present invention is to provide an inverter for converting a DC input into an AC output and supplying the AC output to a load such as an FL tube, in which the continuation of power supply in the event of an abnormality is stopped to prevent an unexpected situation. Is to do.
[0017]
It is another object of the present invention to provide an information processing device with improved display reliability.
[0018]
Another object of the present invention is to provide a test method and a test apparatus using an inverter that converts a DC input into an AC output and supplies the AC output to a load. Provide equipment.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, a method for detecting current of an inverter according to the present invention is a method for detecting current of an inverter which converts a DC input into an AC output and supplies the AC output to a load, wherein the method includes the steps of: In this configuration, a change in the circuit current is detected through a change in magnetic flux due to a change in the circuit current of the inverter.
[0020]
When a disconnection discharge that occurs in a current route including a load of an inverter or an approach discharge between high and low voltage portions of a circuit wiring, that is, a ground fault discharge occurs, a change occurs in a circuit current of the inverter, and the change is caused by a change in the circuit wiring or the transformer. Causes a magnetic flux change between the core gaps. Therefore, if the change in the circuit current is detected by using the change in the magnetic flux as a medium, the change in the circuit current can be detected in a non-contact manner with the circuit wiring, the transformer, and the like, and the abnormality such as discharge occurring in the current route can be known from the change. be able to.
[0021]
In order to achieve the above object, a current detection circuit for an inverter according to the present invention is a current detection circuit for an inverter that converts a DC input into an AC output and supplies the AC output to a load, wherein the current detection circuit is generated due to discharge. The configuration includes a current detection unit 30 that detects a change in the circuit current through a change in magnetic flux due to a change in the circuit current of the inverter.
That is, a change in magnetic flux is detected by the current detector, and a change in circuit current is taken out of the circuit wiring in a non-contact manner by the change in magnetic flux. Therefore, it is possible to know an abnormality such as a disconnection discharge or a ground fault discharge that has occurred in the current route.
[0022]
In order to achieve the above object, in the current detection circuit for an inverter according to the present invention, the current detection unit is installed adjacent to a circuit gap of the inverter (16 or the like) or a core gap of a transformer (inverter transformer 22). The detection conductor (current detection line 36) may detect a change in magnetic flux generated between the circuit wiring or the core gap of the transformer. With this configuration, if the circuit current changes due to disconnection discharge or ground fault discharge in the current route, a corresponding magnetic flux change occurs between the circuit wiring and the core gap of the transformer, and this magnetic flux change is detected. Acts on conductors to generate high voltages. Since this high voltage depends on the change in the circuit current due to the change in magnetic flux, the change in the circuit current can be easily detected by this high voltage, and it is possible to know abnormalities such as disconnection discharge and ground fault discharge that have occurred in the current route. it can. In this case, since the change of the magnetic flux is detected, it does not affect the circuit on the inverter side, and regardless of the operation of the inverter, the change of the circuit current can be detected accurately without contacting the circuit wiring, etc. without malfunction. This eliminates the need for a differentiating circuit and the like, and does not complicate the circuit configuration.
[0023]
In order to achieve the above object, a method for detecting abnormality of an inverter according to the present invention is a method for detecting abnormality of an inverter which converts a DC input into an AC output and supplies the AC output to a load, wherein the method includes the steps of: In this configuration, a change in the circuit current is detected through a change in magnetic flux due to a change in the circuit current of the inverter, and based on the detection result, whether or not the current route including the load has an abnormality is detected.
[0024]
With this configuration, it is easy to determine whether or not the current route including the load has an abnormality based on whether or not the level of the change in the circuit current detected in a non-contact manner through the change in the magnetic flux has exceeded a predetermined level. be able to.
[0025]
In order to achieve the above object, an abnormality detection circuit for an inverter according to the present invention is an abnormality detection circuit for an inverter 2 that converts a DC input into an AC output and supplies the AC output to a load (FL tube 4). A detection unit 30 and a detection signal output unit (comparator 34) are provided. The current detector is configured to detect a change in the circuit current through a magnetic flux change caused by a change in the circuit current of the inverter caused by the discharge.The detection signal output unit is configured to detect a change in the circuit current based on a detection result of the current detector. , And outputs a detection signal indicating whether there is an abnormality in the current route including the load.
[0026]
In such a configuration, when a high voltage output is supplied from the inverter (2) to a load such as the FL pipe (4), an abnormality such as a disconnection discharge or a ground fault discharge occurs in a current route between the inverter and the load. Then, the circuit current of the inverter changes, and this change in the circuit current causes a magnetic flux change Δφ in the circuit wiring (14, 16, 52, 54, 70, 72). In an inverter that supplies a high-voltage output to a load, even if the current route is broken, a discharge occurs at the broken portion and the current route is maintained. In this case, the continuation of the discharge causes a change in the circuit current, causing a change in magnetic flux in the circuit wiring. Also, a sudden change in the circuit current is caused by a ground fault discharge due to insulation breakdown between the high voltage section and the low voltage section on the output side, and this causes a rapid magnetic flux change Δφ in the circuit wiring. A change in the circuit current is detected by the current detecting unit by the action of the magnetic flux change, and a high voltage representing the change is extracted. As a result, a detection signal indicating whether or not there is an abnormality such as a disconnection discharge or a ground fault discharge in the current route including the load such as the FL tube is obtained from the detection signal output unit. Therefore, it is possible to indirectly determine whether there is an abnormality in the current route without touching the circuit current or voltage on the inverter side.
[0027]
In this case, since the change in the circuit current is detected through the change in the magnetic flux, the change in the circuit current can be detected in a non-contact manner regardless of the circuit configuration on the inverter side without making any changes to the circuit conditions of the inverter. It is possible to detect, and to know whether or not there is an abnormality in the current route.
[0028]
In order to achieve the above object, in the inverter abnormality detection circuit according to the present invention, the inverter includes a control unit (an inverter control unit 20) that receives the detection signal and stops the inverter operation when the operation is abnormal. Is also good. When an abnormality such as a disconnection discharge or a ground fault discharge occurs in the current route, the operation of the inverter is stopped, so that the inverter and the load are protected from the continuation of the operation abnormality.
[0029]
In order to achieve the above object, a display device of the present invention includes a current detection circuit of the inverter or an abnormality detection circuit of the inverter, and is configured to display an abnormality or an operation stop of the inverter when an abnormality occurs.
[0030]
The display of this display device includes an image display, a buzzer sound, and other audio notifications. Therefore, the display device receives the detection signal from the detection signal output unit,
(1) Display indicating abnormalities such as disconnection discharge and ground fault discharge,
(2) Stop display of inverter operation,
(3) Indication of (1) or (2) or both indications
I do. From these displays, it is possible to easily know the operation abnormality and the inverter operation stop, and it is possible to take necessary measures as quickly as possible.
[0031]
In order to achieve the above object, an information processing apparatus according to the present invention has a configuration including the inverter current detection circuit, the inverter abnormality detection circuit, or the display device. According to such an information processing apparatus, a power supply system such as a power supply circuit can be configured in addition to a lighting device that drives an illumination load such as a discharge tube using the inverter according to the present invention. If an information processing device is configured using the current detection circuit and the abnormality detection circuit of such an inverter, an operation abnormality such as discharge can be found immediately, or the continuation of the operation abnormality can be avoided. The display or the operation stop can be displayed, so that the display device can be protected. Further, the reliability of the power supply device of various circuits can be improved, the information processing device can be protected from the continuation of abnormal operation of the power supply system, and the reliability of operation can be improved.
[0032]
In order to achieve the above object, a test method of the present invention is a test method using an inverter that converts a DC input into an AC output and supplies the AC output to a load. The configuration is such that the change in the circuit current is detected by using the change in magnetic flux due to the change in the circuit current as a medium, and whether or not the current route including the load has an abnormality is determined based on the detection result.
[0033]
In order to achieve the above object, a test apparatus of the present invention converts a DC input into an AC output and supplies the AC output to a load, and an inverter that supplies the AC output to a load. A current detection unit that detects a change in the circuit current by using a change in magnetic flux as a medium, and determines whether there is an abnormality in a current route including the load based on a detection result of the current detection unit.
[0034]
With such a configuration, a change in circuit current due to a disconnection discharge or a ground fault discharge in the current route is detected through a change in magnetic flux, and abnormalities such as a disconnection discharge or a ground fault discharge in the current route are easily detected from the detection result. Detected with high accuracy. In addition, this test can determine whether or not there is an abnormality without any electrical influence on the current route on the load side using the inverter as a power supply.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the inverter current detection method, the current detection circuit, the abnormality detection method, and the abnormality detection circuit of the present invention will be described with reference to FIG. FIG. 1 shows an FL tube lighting device according to an embodiment of the present invention. The FL tube lighting device 1 constitutes a backlight FL tube lighting device for a liquid crystal display (LCD).
[0036]
The FL tube lighting device 1 includes an inverter 2 for converting a DC input into an AC output, and an FL tube 4 as a load to which the AC output is supplied. The inverter 2 has a disconnection discharge or insulation generated in circuit wiring. An abnormality detection circuit 6 for detecting a destructive discharge is connected.
[0037]
In the inverter 2, a DC power supply 12 is connected to DC input terminals 8 and 10 that receive DC input, and a DC input to be converted to AC is applied. The DC power supply 12 includes various DC power supplies such as an AC-DC converter in addition to a battery.
Further, the DC input terminals 8 and 10 are connected to circuit wirings 14 and 16 to form a current route of the DC input current, and are connected to an input smoothing capacitor 18. The circuit wirings 14 and 16 are formed of, for example, a conductor pattern on a printed wiring board, and the input smoothing capacitor 18 forms a filter that removes a fluctuation component such as a voltage ripple included in the DC input. DC input is smoothed and stabilized. The DC input is supplied to the inverter control unit 20 through the DC input terminals 8 and 10 and the circuit wirings 14 and 16. The inverter control unit 20 includes, for example, a push-pull type inverter circuit unit including a plurality of transistors as a switching element, a drive circuit unit, a switching control unit, and the like. An oscillation circuit included in the feedback circuit is configured. In this embodiment, a switch 26 is built in as a means for switching power supply to the circuit wiring 14. The operation of the switch 26 can be externally switched by a control input applied to a latch input terminal 28 as a control input unit of the inverter control unit 20. The inverter control unit 20 may be a known one such as a general-purpose control IC (for example, TI, TL5001, etc.) that is already on the market, and the details of the circuit configuration will be omitted.
[0038]
In the inverter 2, the abnormality detection circuit 6 for detecting an operation abnormality includes a current detection unit 30 for detecting a circuit current, a current change detection unit 32 for detecting a change in the circuit current caused by the discharge, A comparator 34 is provided as a determination unit for determining whether the change level of the circuit current is abnormal.
[0039]
The current detection unit 30 is a circuit unit that detects a change in circuit current by using a change in magnetic flux generated by a change in circuit current from the circuit wiring 16 or the like of the inverter 2 as a medium. The 16th side is set as a current detection site. In the current detection unit 30, a current detection line 36 is provided as a detection conductor for detecting a change in circuit current through a change in magnetic flux Δφ generated in the circuit wiring 16. In this case, the DC input current i _d Is a detection target. The current detection line 36 is a wiring conductor provided along with the circuit wiring 16 at an interval capable of capturing a magnetic flux change Δφ generated in the circuit wiring 16.
[0040]
Next, the current detection unit 30 will be described with reference to FIG. FIG. 2 shows an example of the current detection unit 30. The current detection unit 30 includes a current detection line 36 having the same wiring pattern as the circuit wiring 16 installed on the printed wiring board 38. In the present embodiment, the wiring pattern of the circuit wiring 16 and the wiring of the current detection line 36 are used. The pattern forms a parallel pattern. That is, the current detection line 36 having a linear portion parallel to the linear circuit wiring 16 is provided, and the DC input current i _d Causes the magnetic flux change Δφ generated in the circuit wiring 16 to act on the current detection line 36. In this case, a is the width of the current detection line 36, b is its length, and a predetermined insulation interval D is set between the current detection line 36 and the circuit wiring 16. If the insulation interval D is reduced, the detection sensitivity of the magnetic flux change Δφ can be increased.
[0041]
The current detection line 36 is provided with detection terminals 40 and 42 for extracting a voltage generated by the action of the magnetic flux change Δφ, and the detection voltages obtained at the detection terminals 40 and 42 are currents for detecting a change in circuit current. It is added to the change detection unit 32. In the case of this embodiment, the current change detection unit 32 includes a diode 44 as a conversion unit that rectifies the detection voltage and converts the voltage into a DC level. The diode 44 is connected to the detection terminal 40 side. Between the cathode side and the detection terminal 42, a capacitor 46 is provided as a filter circuit, and a resistor 48 constituting a detection level adjustment unit is connected. As the diode 44, for example, a Schottky diode having a short reverse recovery time is used in order to respond to the detection of a current change due to disconnection discharge or the like. With such a configuration, the current change detection unit 32 is configured as a current / voltage conversion unit that converts a change in circuit current into a change in DC voltage, and a DC voltage corresponding to the change in circuit current is obtained in the capacitor 46 and the resistor 48. This voltage level is the change in the circuit current, in this case the DC input current i _d Represents the change of
[0042]
The detection signal of the current change detection section 32 is applied to a comparator 34 constituting a detection signal output section. The comparator 34 constitutes an amplifying unit for the detection signal, and is a determination unit that determines whether or not the operation is abnormal based on the change level of the circuit current, and compares the detection signal with a predetermined level indicating the operation abnormality. In this case, the predetermined level is, for example, a reference level at which an operation abnormality such as a disconnection discharge of a circuit wiring or an approach discharge (dielectric breakdown discharge) between a high voltage portion and a low voltage portion of the circuit wiring can be determined. Any level setting may be used as long as it can be determined whether it is abnormal or normal, such as a level during operation or a level slightly higher than the level. Therefore, the comparator 34 compares the detection voltage with a predetermined level. For example, when the level of the detection voltage is equal to or lower than the predetermined level, the low (L) level indicating normal, and when the level of the detection voltage exceeds the predetermined level, A detection signal Vs having a high (H) level indicating an abnormal operation is output. The detection signal Vs is applied to the latch input terminal 28 of the inverter control unit 20 and is used to maintain the operation of the inverter control unit 20 in a normal state and to stop the operation of the inverter control unit 20 in an abnormal operation. In this embodiment, when the operation is abnormal, the switch 26 is opened by the detection signal Vs applied to the latch input terminal 28, the power supply to the inverter control unit 20 is released, and the operation of the inverter 2 is controlled to a stopped state.
[0043]
Further, circuit wirings 52 and 54 are connected to the secondary winding 50 of the inverter transformer 22 to form a current route of the output current. A ballast capacitor 56 is inserted in one circuit wiring 52 and a connection connector 58 as an AC output terminal is inserted. A constant current detection resistor 60 is inserted in the other circuit wiring 54 and a connection connector 62 as an AC output terminal is inserted. The FL tube 4 as a load is connected to the connection connectors 58 and 62, and the FL tube 4 constitutes a backlight of the LCD 64. The ballast capacitor 56 constitutes a stabilizer for stabilizing the tube current flowing through the FL tube 4, and the tube current detected by the constant current detection resistor 60 is applied to the inverter control unit 20 side, thereby making the tube current constant. Used for Therefore, as a switching operation of the inverter control unit 20, an alternating current is generated by an orthogonal transformation operation, and a high-frequency high-voltage output is obtained in the secondary winding 50 of the inverter transformer 22 by boosting the inverter transformer 22. This high voltage output is applied to the FL tube 4 through the circuit wirings 52 and 54 and the connection connectors 58 and 62. In this embodiment, a case where a single FL tube 4 is connected to a single secondary winding 50 is shown. However, a plurality of FL tubes may be installed, in which case the ballast capacitor 56 is connected to each FL tube. Installed for each pipe.
[0044]
Next, the operation of the FL tube lighting device 1 will be described with reference to FIGS. 3A shows an operation waveform in a normal state, FIG. 3B shows an operation waveform in an abnormal state, and FIG. 4 shows a case where a disconnection discharge or a ground fault discharge occurs in a current route.
[0045]
When the FL tube 4 is driven at a constant current using such an inverter 2, the FL tube 4 is turned on by a constant drive current. When the operation is normal, the operation waveform of the AC output is a sine wave waveform nw shown in FIG. 3A. For example, as shown in FIG. A discharge occurs at 66, which maintains the current route. As shown in FIG. 3B, the operation waveform at the time of such an abnormal operation is an abnormal waveform in which the discharge waveform dw is superimposed on the normal sine wave waveform nw. The discharge waveform dw changes more rapidly than the gradual AC output fundamental wave and is a noise (high frequency) having a high frequency component. Such a waveform component does not increase the current value of the circuit current. It only increases the amount of change. Then, the discharge waveform dw is periodically generated with respect to a level change of the sine wave waveform nw in a normal state. Such a phenomenon can be applied not only to the current waveform but also to the voltage waveform, but it has been experimentally confirmed that the change of the current waveform is larger than that of the voltage waveform.
[0046]
When the current route is maintained by such discharge, the output current i of the inverter transformer 22 ₂ , The input current i of the inverter transformer 22 ₁ , DC input current i _d The circuit current such as the drive current in the inverter control unit 20 changes suddenly, and a violent magnetic flux change Δφ indicating a sudden change in the circuit current occurs around the circuit wirings 14 and 16 constituting the current route. At this time, an abrupt change in magnetic flux Δφ is detected in the current detection line 36, and a high voltage representing a change in circuit current is generated at both ends. This high voltage is rectified by the diode 44 and smoothed by the capacitor 46, so that a DC voltage having a level representing a rapid current change is obtained at the time of discharging. This DC voltage is applied to a comparator 34 and compared with a predetermined level, and the comparator 34 obtains a detection signal Vs indicating whether the operation is normal or abnormal.
[0047]
When the detection signal Vs is applied to the latch input terminal 28 of the inverter control unit 20 as an operation stop output, the inverter control unit 20 turns off the switch 26, stops the inverter operation, and cancels the AC output. The FL tube 4 is turned off and the continuation of the discharge is interrupted. As a result, the inverter 2 and the FL tube 4 are released from the continuation of the operation abnormality.
[0048]
Also, as shown by a broken line in FIG. 4, when a discharge 68 occurs due to dielectric breakdown or the like due to an approach between a high-voltage section on the AC output side and a low-voltage section such as a chassis, the operation waveform is shown in FIG. As shown, similar to the disconnection discharge, an abnormal waveform is obtained in which the discharge waveform dw is superimposed on the normal sine wave waveform nw.
[0049]
Also in this case, a sudden change in the circuit current of the circuit wiring 16 causes a magnetic flux change Δφ, which is detected by the current detection line 36 of the current detection unit 30. Is obtained. As a result, the inverter operation by the inverter control unit 20 is stopped, and the release of the AC output turns off the FL tube 4 and interrupts the continuation of the discharge. Similarly, the inverter 2 and the FL tube 4 are released from the continuation of the operation abnormality.
[0050]
The operation and effect of this embodiment are as follows.
[0051]
In this embodiment, since the current detection unit 30 is provided on the input current side of the inverter control unit 20, a sudden change of the input current caused by an operation abnormality such as disconnection discharge or dielectric breakdown discharge of the output side current route is detected by a magnetic flux change Δφ. Thus, a high voltage indicating an abnormal operation can be generated at the detection terminals 40 and 42. That is, as compared with the detection of an operation abnormality on the high voltage side, insulation measures are easier and safety is excellent.
[0052]
Since the change in the circuit current is detected through the magnetic flux change Δφ, a voltage representing a sudden change in the circuit current is generated by an extremely simple configuration in which the current detection line 36 is arranged in parallel with the circuit wiring 16. Can be extracted at a high voltage. That is, the detection sensitivity of the change in the circuit current is high, and the abnormal operation can be detected with high accuracy.
[0053]
In addition, an operation abnormality such as discharge can be detected from a voltage change, but since a change in circuit current is detected through a change in magnetic flux Δφ, detection accuracy is increased. That is, the waveform change due to the discharge has a larger change in the current waveform than the voltage waveform, and the change in the current causes a change in the magnetic flux Δφ, so that the detection of the operation abnormality through the change in the magnetic flux Δφ increases the detection accuracy.
[0054]
When detecting a change in the circuit current through the magnetic flux change Δφ, the magnetic flux change Δφ can be easily detected with a very simple configuration in which the current detection line 36 is arranged in parallel with the circuit wiring 16. The installation of 36 does not require any change to the circuit conditions on the inverter 2 side, and the current change detection unit 32 and the comparator 34 respond to the high voltage generated at the detection terminals 40 and 42 irrespective of the inverter side circuit. The circuit can be configured by means of a simple circuit design.
[0055]
The current change detection unit 32 determines whether the high voltage obtained at the detection terminals 40 and 42 is normal by a simple circuit configuration and processing such as rectification by a diode 44 and smoothing by a capacitor 46, and whether the operation is abnormal due to discharge. And a DC voltage at a level required for the above. That is, it is possible to generate a DC voltage in which the level difference clearly indicates whether the operation is normal or abnormal due to discharge. Therefore, in the comparator 34, it is easy to set a reference level for distinguishing between normal and abnormal, and as a result, it is possible to detect an operational abnormality with high detection accuracy and without malfunction.
[0056]
Then, by applying the detection signal Vs obtained from the comparator 34 to the latch input terminal 28 of the inverter control unit 20, the operation of the inverter control unit 20 is stopped when the operation is abnormal. The load on the tube 4, the LCD 64, and the like can be protected.
[0057]
By the way, according to an experiment, a Schottky diode having a fast reverse recovery time is used as the diode 44 of the current change detection unit 32 for generation of a detection voltage irrelevant to disconnection discharge or dielectric breakdown discharge in the current detection line 36. The resistance of the resistor 48 is, for example, 0.1 [MΩ] to 5 [MΩ], and the capacitor 46 is, for example, a capacitance of 0.0015 [μF] to 0.1 [μF]. It has been confirmed that by setting the circuit conditions described above, it is possible to detect a voltage change due to a change in the circuit current due to the minute discharge. As a result, abnormalities such as disconnection discharge, dielectric breakdown discharge, and ground fault discharge can be detected, and malfunction due to a transient current due to power-on can be easily prevented. In this case, specific circuit conditions used in the experiment are shown for the diode 44, the capacitor 46, and the resistor 48, but these circuit conditions can be arbitrarily set, and the present invention is limited to such circuit conditions. Not something.
[0058]
Next, a current detection portion for detecting a change in circuit current will be described with reference to FIG. FIG. 5A shows a case where the current detection part is set on the primary side of the inverter transformer, and FIG. 5B shows a case where the current detection part is set on the secondary side of the inverter transformer.
[0059]
For example, as shown in FIG. 5A, the current detection parts include circuit wirings 70 and 72 connected to the primary winding 24 of the inverter transformer 22, as shown in FIG. For example, the current detection unit 30 may be provided on the circuit wiring 72 and the current detection line 36 may be provided along with the secondary winding 50 of the inverter transformer 22 as shown in FIG. May be set as current detection sites. For example, the current detection unit 30 may be installed on the circuit wiring 54 and the current detection line 36 may be provided. When the current detection line 36 is provided along with the circuit wiring 72, the primary current flowing through the circuit wirings 70 and 72 on the primary winding 24 side of the inverter transformer 22, that is, the input current i ₁ Can be detected through the magnetic flux change Δφ due to the change of the inverter, and the inverter operation can be stopped.
[0060]
In addition, if the current detection line 36 is provided in parallel with the circuit wiring 54, the output current i which is the secondary current of the inverter transformer 22 flowing through the circuit wiring 54 ₂ And the output current i ₂ , The inverter operation is stopped when the operation is abnormal, and the inverter 2, the FL tube 4, etc. can be protected from the continuation of the operation abnormality such as discharge. In this case, the output side of the inverter transformer 22 has a large waveform change and a large change value of the discharge waveform as compared with the input side, so that the change in the detected circuit current and the change in the magnetic flux are large, and the detection accuracy is high. Become.
[0061]
Next, another embodiment of the current detection unit 30 will be described with reference to FIG. 6A is a current detection unit 30 configured using a core, FIG. 6B is a current detection unit 30 configured by winding a current detection wire around a core, and FIG. The current detection unit 30 is configured by winding the current detection line 36 around the circuit wirings 16, 54, and 72.
[0062]
For example, as shown in FIG. 6A, a ring-shaped core 74 is installed in the current detection unit 30, and the circuit wiring 16, 54 or 72 and the current detection By passing the wire 36, a common magnetic path for passing the magnetic flux φ to the current detection line 36 may be formed together with the circuit wiring 16, 54 or 72 with the core 74. When such a core 74 is used, the magnetic flux change Δφ can be increased by the magnetic permeability μ of the magnetic material forming the core 74, the detection voltage of the detection terminals 40 and 42 can be increased, and the detection sensitivity can be increased. .
[0063]
Further, for example, as shown in FIG. 6B, the current detection line 36 may be wound around the core 74. In this case, the magnetic flux change Δφ acting on the current detection line 36 is increased by the number of turns N, the detection voltage generated at the detection terminals 40 and 42 is boosted, and a higher detection voltage can be taken out. In this case, the circuit wiring 16, 54 or 72 may be wound around the core 74. Further, a rod-shaped core may be used as the core 74, and a common magnetic path can be similarly formed in the circuit wiring 16, 54 or 72 and the current detection line 36 with the rod-shaped core.
[0064]
For example, as shown in FIG. 6C, the current detection line 36 is wound around the circuit wiring 16, 54, or 72 several times, and the magnetic flux change Δφ generated in the circuit wiring 16, 54, or 72 is applied to the current detection line 36. You may make it act. With such a configuration, a detection voltage corresponding to the number of turns of the current detection line 36 can be extracted between the detection terminals 40 and 42. If the configuration is such that the core 74 is not used, the number of components is small and the current detection unit 30 can be configured at low cost. For example, the same effect can be obtained in the abnormality detection circuit 6 of the inverter 2 shown in FIGS. 1, 4, and 5 in which the core 74 is not used.
[0065]
Next, another embodiment of the current detection unit 30 will be described with reference to FIGS. FIG. 7 shows a current detection unit 30 installed adjacent to the inverter transformer, and FIG. 8 shows detection of a change in magnetic flux caused by a discharge current.
[0066]
The inverter transformer 22 used in the inverter 2 has a gap 25 formed in the core 23, and the gap 25 is installed with the gap 25 facing the printed wiring board 38. Therefore, a current detection line 36 is provided on the printed wiring board 38 between the gaps 25 by a wiring pattern. In other words, a current detection line 36 having a width a and a length b smaller than the interval w between the cores 23 is formed on the printed wiring board 38, and the core 23 of the inverter transformer 22 is installed across the printed wiring board 38. The current detection line 36 is arranged between the gaps 25. The length b of the current detection line 36 is set larger than the width d of the core 23, but may be set to the same length (b = d). The primary winding 24 and the secondary winding 50 are installed in the inverter transformer 22. The terminals 24 a and 24 b of the primary winding 24 are connected to the inverter control unit 20, and the terminal 50 a of the secondary winding 50 is connected to a ballast capacitor 56. (FIG. 1), a constant current detection resistor 60 is connected to the terminal 50b.
[0067]
With such a configuration, for example, when a discharge occurs in the current route on the secondary winding 50 side of the inverter transformer 22, the discharge current causes a rapid magnetic flux change Δφ in the gap 25 as shown in FIG. . This magnetic flux change Δφ acts on the gap 25 and the current detection line 36 adjacent thereto and is detected by the current detection line 36, and the circuit current (i _d ), A detection voltage having a high level indicating the change of the detection voltage is obtained. This detection voltage is applied to the current change detection unit 32 (FIG. 1) and used for inverter control and the like.
[0068]
Next, an embodiment of the display device of the present invention will be described with reference to FIG. FIG. 9 shows a display device using the inverter abnormality detection circuit according to the present invention.
[0069]
In this display device, the configurations, operations, and effects of the inverter 2 and the abnormality detection circuit 6 are as described with reference to FIGS.
[0070]
In this display device, an LCD 64 and an indicator 76 which constitute a display unit for displaying the abnormality at the time of abnormal operation are installed, and a processor 78 is installed as a display control unit for these. The processor 78 constitutes a processing unit that executes a control program for displaying an operation abnormality stored in a storage unit (not shown). The processor 78 receives the detection signal Vs obtained by the comparator 34, The keyboard 80 is connected, and an instruction input for executing a process for confirming an operation abnormality is input. The LCD 64 is provided with a display drive unit 82 and the indicator 76 is provided with a display drive unit 84 in order to perform a predetermined display upon receiving a display control output from the processor 78.
[0071]
The operation of this display device will be described with reference to FIG. FIG. 10 is a flowchart showing the operation abnormality confirmation processing. In the operation abnormality confirmation process, it is determined whether or not the operation is in the operation abnormality confirmation mode by starting the process (step S1). In this case, by operating a key assigned to a specific key or a plurality of keys on the keyboard 80, the operation abnormality confirmation mode is set. In this case, the operation abnormality check mode at the time of turning on the power may be automatically set so that the abnormality of the inverter 2 can be confirmed. When the operation abnormality check mode is established, the detection signal Vs from the comparator 34 is accepted, and it is determined whether an operation abnormality has been detected (step S2).
[0072]
During normal operation, the LCD 64 or the indicator 76 displays no operation abnormality, that is, a normal operation is displayed (step S3). For example, when a predetermined time has elapsed from the start of the display of the normal operation, or when the administrator instructs the operation display cancellation from the keyboard 80, the display cancellation is performed (step S4), and thereafter, the process returns to the step S1.
[0073]
When an operation abnormality is detected in step S2, the display of the operation abnormality and the stop of the operation of the inverter 2 are displayed on the LCD 64 or the indicator 76 (step S5). The administrator checks these displays and performs necessary processing. For example, when a predetermined time elapses from the start of the operation abnormality display, or when the administrator instructs the operation display cancellation from the keyboard 80, the display cancellation is performed (step S6), and thereafter, the process returns to step S1. In this case, when the operation abnormality is displayed, the display may not be released unless the administrator performs a predetermined improvement process.
[0074]
When the FL tube 4, which is the light source of the LCD 64, is turned off, it is expected that the display contents of the LCD 64 will be difficult to confirm. Therefore, the indicator 76 is easy to confirm when an abnormality is displayed or when the operation of the inverter 2 is stopped. Can be used for an abnormality display or a display indicating that the operation of the inverter 2 has stopped. If the display can be confirmed with the FL tube 4 turned off, the indicator 76 is not necessarily required. If such display is performed using both the LCD 64 and the indicator 76, the operation can be stopped and the reliability of the display can be improved.
[0075]
Next, an embodiment of an information processing apparatus and an electronic apparatus according to the present invention will be described with reference to FIG. FIG. 11A shows a mobile phone according to the embodiment, and FIG. 11B shows a notebook personal computer according to the embodiment. The mobile phone and the notebook personal computer constitute an information processing device and an electronic device configured using the inverter abnormality detection circuit or the display device according to the present invention.
[0076]
As this information processing device or electronic device, a FL tube 4 is installed as a backlight of an LCD 64 as a display device in a housing 90 of a mobile phone 86 or a notebook personal computer 88, and a driving device thereof is shown in FIGS. A processor 78, a keyboard 80, and the like are incorporated as an arithmetic and control unit together with the inverter 2 shown and the abnormality detection circuit 6 of the inverter 2 according to the present invention. In this case, the indicator 76 as a display element may be installed for maintenance in the housing 90 of the mobile phone 86 or the notebook personal computer 88, or may be installed on the outer surface of the housing 90.
[0077]
With such a configuration, in information processing apparatuses such as the mobile phone 86 and the notebook personal computer 88, disconnection discharge and insulation breakdown of the circuit wirings 14 and 16, the circuit wirings 52 and 54, and the circuit wirings 70 and 72 of the inverter 2 are provided. An operation abnormality such as discharge can be monitored, and by stopping the operation, the information processing apparatus can be protected from the continuation of the operation abnormality. Further, since the operation abnormality and the operation stop are displayed on the LCD 64 and the indicator 76, the operation abnormality and the operation stop can be quickly known from the display, and a highly reliable information processing apparatus can be realized. Moreover, abnormalities such as disconnection discharges and dielectric breakdown discharges of the circuit wirings 14 and 16 of the inverter 2 can be easily determined from the displayed contents, and necessary countermeasures can be immediately executed, and a highly safe information processing device or electronic device. Can be provided.
[0078]
Next, an embodiment of a test method and a test apparatus of the present invention will be described with reference to FIGS. FIG. 12 is a view showing a test apparatus according to the embodiment, and FIG. 13 is a flowchart showing a test procedure.
[0079]
A liquid crystal display unit 92 is used as a test object. In this case, the liquid crystal display unit 92 includes an LCD 64 and an FL tube 4, and the FL tube 4 has connection connectors 58 and 62, and the LCD 64 has a connection connector 94. I have.
[0080]
The test device 96 of the liquid crystal display unit 92 includes the inverter 2 including the abnormality detection circuit 6 described above with reference to FIG. 1, and in the present embodiment, the processor described above with reference to FIG. 78, and display drive units 82 and 84 are provided. The output of the display driver 84 is applied to a display 98, and the display 98 displays the test result. Other configurations are the same as those shown in FIGS. 1 and 9.
[0081]
In testing the liquid crystal display unit 92, the AC output unit of the inverter 2 of the test device 96 is connected to the connection connectors 58 and 62, and the output unit of the display drive unit 82 is connected to the connection connector 94.
[0082]
Then, referring to the flowchart shown in FIG. 13, it is determined whether or not the FL tube 4 has been connected by starting the test (step S11). If the FL tube 4 is connected, the inverter 2 connects the FL tube 4 to the FL tube 4. Power supply is started (step S12). As a result of this power supply, it is determined whether or not the change in circuit current is equal to or higher than a predetermined level (step S13). If disconnection discharge and ground fault discharge have not occurred in the current route on the side of the FL tube 4 as a load, the discharge current is determined. And the change in circuit current is less than a predetermined level. The detection of the change in the circuit current is as described above. In this case, the detection output of the abnormality detection circuit 6 is applied from the comparator 34 to the processor 78 and determined to be normal, and the determination result is displayed on the display 98 as a test result indicating normal (step S14). Further, when a disconnection discharge or a ground fault discharge occurs in the current route on the side of the FL tube 4 as a load, the discharge current causes a large change in the circuit current, and the change becomes a predetermined level or more. The detection of the change in the circuit current is as described above. In this case, the detection output of the abnormality detection circuit 6 is applied to the inverter control unit 20, and the output of the inverter is stopped. At the same time, the detection output is applied from the comparator 34 to the processor 78 and determined to be abnormal, and the result of the determination is displayed on the display 98 as an abnormal test result (step S15).
After stopping the power supply (step S16), the tested liquid crystal display unit 92 is removed from the test device 96, the next liquid crystal display unit 92 is connected to the test device 96, and the same test is performed.
[0083]
According to such a test apparatus and test method, the liquid crystal display unit 92 does not increase the number of test steps, does not require special preparation, and furthermore, the lighting conditions of the liquid crystal display unit 92 are different from those at the time of use. Tests can be performed with the same settings, and it is possible to quickly and accurately test whether or not there is a disconnection discharge or a ground fault discharge, and whether or not there is an abnormality in the connectors 58, 62, and 94. And can contribute to providing a highly reliable product.
[0084]
In this test apparatus, the case where the current detection unit 30 is installed on the circuit wiring 16 on the input side of the inverter control unit 20 has been described, but the current detection unit 30 is installed on the circuit wiring 52 or 54 on the secondary side of the inverter transformer 22. May be installed to detect a change in the circuit current through a change in the magnetic flux Δφ due to a change in the circuit current to determine an abnormality such as discharge of the FL tube 4 or the current route. As described above, detecting a change in the circuit current on the secondary side of the inverter transformer 22 is advantageous in increasing the detection accuracy.
[0085]
In addition, the present invention provides various electronic devices in addition to the inverter current detection method described above, the current detection circuit thereof, the abnormality detection method thereof, the abnormality detection circuit, the display device, the information processing device, the test method and the test device, and the like. Includes Therefore, technical matters are extracted from each embodiment of the present invention, and their technical significance, modified examples, and other technical expansion matters are listed below.
[0086]
a In the embodiment, when a change in the circuit current exceeds a predetermined level, a comparator 34 that compares a detection voltage with a predetermined level and outputs a detection signal as a detection signal output unit that outputs a detection signal indicating an operation abnormality is provided. Although illustrated, the detection signal output unit may be formed using a switching transistor or a switch circuit that is turned on or off in response to the level of the detection signal.
[0087]
b After rectifying the detection voltage obtained at the detection terminals 40 and 42 or extracting a specific frequency component, the digital signal is converted into a digital signal, and the digital signal is added to a processor 78 shown in FIG. The inverter 2 may be configured to determine whether an abnormal operation has occurred in the inverter 2, apply the determination output as a control input to the latch input terminal 28 of the inverter control unit 20, and stop the operation of the inverter 2. . In this case, when the operation is stopped, an operation abnormality such as discharge or the state thereof may be displayed on the LCD 64 or the indicator 76.
[0088]
c Although the circuit wiring 16 and the current detection line 36 shown in FIG. 2 are configured by the conductor pattern of the printed wiring board, the circuit wiring 16 and the current detection line 36 may be configured by wires other than the conductor pattern. The detection lines 36 may be bundled to cause the magnetic flux change Δφ on the circuit wiring 16 side to act on the current detection lines 36.
[0089]
d The current change detection of the current change detection unit 32 is performed by detecting the voltage detected at the detection terminals 40 and 42 by rectifying and smoothing the detected voltage at the detection terminals 40 and 42 with the diode 44, the capacitor 46, and the resistor 48, as well as disconnection discharge and insulation. A detection circuit that detects and extracts a component specific to discharge included in a change in circuit current caused by destructive discharge may be used.
[0090]
e When the inverter control unit 20 does not include the operation stop unit, the control unit that cancels the operation of the inverter 2 is provided to the DC input side of the inverter control unit 20 based on the detection signal Vs at the time of abnormal operation. A switch circuit for canceling power supply may be provided.
[0091]
Although the inverter control unit 20 has been described as an example of the control unit, the power supply control to the inverter control unit 20 may be performed by using the processor 78 as the control unit, and the inverter operation may be stopped when the operation is abnormal.
[0092]
g. The problem to be solved by the present invention addresses the inverter 2 having a constant current drive and a low current output as a conventional technique, but the present invention is not limited to such an inverter.
[0093]
h In the embodiment, the primary winding 24 of the inverter transformer 22 is a single winding for the sake of simplicity, but the feedback to be applied to each transistor of the push-pull type inverter circuit built in the inverter control unit 20. This does not exclude a winding for extracting a signal, and the inverter abnormality detection circuit of the present invention includes various inverters.
[0094]
Next, experimental results of the current detection unit 30 will be described with reference to FIG. Regarding the wiring pattern of the current detection line 36 as a detection conductor (FIG. 2), the width a is set to 10 [mm], the length b is changed, and the distance D = 0 between the circuit wiring 16 and the current detection line 36 is set. When the values were set to 0.1 mm, 0.2 mm, 0.3 mm, and 0.5 mm, the voltage shown in FIG. As is apparent from the experimental results, the current detection line 36 having a width a = 10 [mm] × length b = 10 [mm] is used, and the distance D between the current detection line 36 and the circuit wiring 16 is set to 0.5. When it was set to [mm], it was confirmed that a detection voltage of 2 [V] was obtained by the discharge current. According to this detection voltage, it was confirmed that a change in circuit current due to discharge can be detected with high accuracy.
[0095]
Next, the technical ideas extracted from the above-described embodiments of the present invention will be listed as supplementary notes according to the description form of the claims. The technical idea according to the present invention can be grasped at various levels and variations from a high-level concept to a low-level concept, and the present invention is not limited to the following supplementary notes.
[0096]
(Supplementary Note 1) A current detection method of an inverter that converts a DC input into an AC output and supplies the AC output to a load,
An inverter current detection method, wherein a change in the circuit current is detected through a change in magnetic flux due to a change in the circuit current of the inverter caused by discharging.
[0097]
(Supplementary Note 2) A current detection circuit of an inverter that converts a DC input into an AC output and supplies the AC output to a load,
An inverter current detection circuit, comprising: a current detection unit that detects a change in the circuit current by using a change in magnetic flux due to a change in the circuit current of the inverter caused by the discharge as a medium.
[0098]
(Supplementary Note 3) The current detection unit detects a magnetic flux change occurring between the circuit wiring or the core gap of the transformer by using a detection conductor provided adjacent to the circuit wiring of the inverter or the core gap of the transformer. 2. The current detection circuit for an inverter according to claim 2, wherein
[0099]
(Supplementary Note 4) An abnormality detection method for an inverter that converts a DC input into an AC output and supplies the AC output to a load,
A change in the circuit current is detected through a magnetic flux change caused by a change in the circuit current of the inverter caused by the discharge, and based on the detection result, whether or not the current route including the load is abnormal is detected. A method for detecting abnormality of an inverter.
[0100]
(Supplementary Note 5) An abnormality detection circuit for an inverter that converts a DC input into an AC output and supplies the AC output to a load,
A current detection unit that detects a change in the circuit current through a change in magnetic flux due to a change in the circuit current of the inverter caused by the discharge;
A detection signal output unit that outputs a detection signal indicating whether there is an abnormality in the current route including the load, based on a detection result of the current detection unit;
An abnormality detection circuit for an inverter, comprising:
[0101]
(Supplementary note 6) The inverter abnormality detection circuit according to supplementary note 5, wherein the inverter includes a control unit that receives the detection signal and stops the inverter operation when the operation is abnormal.
[0102]
(Supplementary Note 7) A display characterized by comprising a current detection circuit of the inverter according to Supplementary Note 2 or an abnormality detection circuit of the inverter according to Supplementary Note 5, and configured to display, when an abnormality occurs, the abnormality or the operation stop of the inverter. apparatus.
[0103]
(Supplementary Note 8) An information processing apparatus comprising the inverter current detection circuit according to Supplementary Note 2, the inverter abnormality detection circuit according to Supplementary Note 5, or the display device according to Supplementary Note 7.
[0104]
(Supplementary Note 9) A test method using an inverter that converts a DC input into an AC output and supplies the AC output to a load,
Detecting a change in the circuit current through a change in a magnetic flux due to a change in the circuit current of the inverter caused by the discharge, and determining whether there is an abnormality in a current route including the load based on the detection result. A test method characterized by the following.
[0105]
(Supplementary Note 10) An inverter that converts a DC input into an AC output and supplies the AC output to a load;
A current detection unit that detects a change in the circuit current, through a change in magnetic flux due to a change in the circuit current of the inverter caused by the discharge,
A test apparatus configured to determine whether a current route including the load has an abnormality based on a detection result of the current detection unit.
[0106]
(Supplementary Note 11) The abnormality detection circuit of the inverter includes a current change detection unit. The current change detection unit includes a rectification unit that rectifies a fluctuating voltage obtained by a magnetic flux change, and includes a smoothing unit that smoothes the rectified voltage. An inverter abnormality detection circuit having a configuration provided with the inverter. With this configuration, a detection signal having a level proportional to a change in the circuit current can be accurately obtained on the detection conductor, so that a change in the circuit current due to a minute discharge can be detected, and the detection accuracy can be improved. Can be.
[0107]
(Supplementary Note 12) In the abnormality detection circuit for an inverter, the current change detection unit includes a rectification unit that rectifies a fluctuating voltage obtained by a change in magnetic flux, and the rectification unit includes a Schottky diode. Abnormality detection circuit.
Since a Schottky diode has a faster reverse recovery time than a high-speed diode, it can rectify the change in circuit current due to discharge and the noise component due to discharge and extract it as a DC component. Detection can be performed, detection accuracy can be improved, and malfunction can be prevented.
[0108]
(Supplementary Note 13) In the inverter abnormality detection circuit, the current change detection unit includes a filter that extracts a current change caused by a discharge such as a disconnection discharge or a dielectric breakdown discharge. With this configuration, a change in circuit current due to discharge can be accurately detected except for a transient current change such as when the power is turned on, and malfunction can be prevented.
[0109]
(Supplementary Note 14) In the current detection circuit of the inverter, the current detection unit includes a part of the circuit wirings 14, 16, 52, 54, 70, and 72 and the detection conductor (current detection line 36) as independent discrete elements. A current detection circuit for an inverter. According to this configuration, the inverter 2 can be installed at an arbitrary position of the circuit wiring of the inverter 2, for example, the circuit wiring 14, 16, 52, 54, 70, 72 to protect the inverter or the like from continuation of abnormal operation such as discharge. Reliability can be improved.
[0110]
(Supplementary Note 15) In the current detection circuit of the inverter, the current detection unit may be any part of circuit wiring from a DC input to a load, a DC input side, a primary side of the inverter transformer 22 or a secondary side thereof, or An inverter current detection circuit, which is installed at a plurality of locations. That is, an operation abnormality such as discharge can be detected at an arbitrary position of the circuit wirings 14, 16, 52, 54, 70, 72.
[0111]
(Supplementary Note 16) The abnormality detection circuit for an inverter according to the above-mentioned inverter, wherein a display drive unit is incorporated in the control unit, and an output of the display drive unit is added to an indicator so that an operation abnormality can be displayed. That is, by displaying the operation abnormality or the operation stop of the inverter, the abnormal state can be easily grasped.
[0112]
(Supplementary Note 17) In the inverter abnormality detection circuit, the inverter control unit 20, the current change detection unit 32, and the comparator 34 are configured by a single IC. With this configuration, the reliability of the abnormality detection circuit of the inverter can be enhanced by a single IC, and the commercial value of the control IC, which is a component of the inverter, can be improved, and at the same time, the number of components can be reduced. Can be achieved.
[0113]
(Supplementary Note 18) The abnormality detection circuit of the inverter includes a core 74 that forms a common magnetic path with the circuit wirings 14, 16, 52, 54, 70, 72 and the detection conductor (current detection line 36). Inverter abnormality detection circuit. That is, for example, if a common magnetic path is configured to the circuit wirings 16, 54, 72 and the detection conductor using the core 74, the magnetic flux change Δφ on the circuit wirings 16, 54, 72 side can be efficiently transmitted to the detection conductor through the core 74. In this case, the magnetic flux can be enhanced by the magnetic permeability of the core 74 and applied to the detection conductor (current detection line 36), so that the detection accuracy of the change in the circuit current can be improved. The protection function of the inverter 2 and the load at the time of abnormality can be further enhanced. The change in magnetic flux can be increased by the magnetic permeability of the magnetic material of the core 74 which is a common magnetic path, and the detection sensitivity of the current change can be increased.
[0114]
(Supplementary Note 19) In the information processing device described above, the inverter is used for a power supply device or a FL tube lighting device. With this configuration, a highly reliable information processing device can be provided.
[0115]
(Supplementary Note 20) A lighting device comprising the inverter abnormality detection circuit. That is, the detection of the inverter disconnection discharge and the dielectric breakdown discharge, the operation stop, and the display accompanying the operation can be performed, so that a highly reliable lighting device can be provided.
[0116]
As described above, the most preferred embodiment of the present invention has been described, but the present invention is not limited to the above description, but is described in the claims or disclosed in the detailed description of the invention. Of course, various modifications and changes can be made by those skilled in the art based on the gist of the invention made, and it goes without saying that such modifications and changes are included in the scope of the present invention.
[0117]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
(1) According to the current detection method or current detection circuit for an inverter of the present invention, a magnetic flux change caused by a change in circuit current caused by a discharge such as a disconnection discharge or a ground fault discharge occurring in a current route including a load of the inverter. , The change in the circuit current is detected, so that a change in current caused by a disconnection discharge, a ground fault discharge, or the like can be reliably detected without contacting the circuit wiring, and an abnormality such as a disconnection can be found.
[0118]
(2) In the current detection method or the current detection circuit of the inverter according to the present invention, the current detection unit is formed by a detection conductor disposed adjacent to between the circuit gap of the inverter or the core gap of the transformer. If a configuration for detecting a magnetic flux change occurring between them is used, a detection conductor is arranged close to the circuit wiring to detect a change in circuit current through the magnetic flux change, so that only a detection conductor is provided in the circuit wiring. With a simple configuration and non-contact with the circuit wiring, it does not affect the circuit conditions of the inverter or load, and does not affect the current detection. Can be detected with high accuracy.
[0119]
(3) According to the inverter abnormality detection method and the abnormality detection circuit according to the present invention, it is possible to eliminate malfunctions such as disconnection discharge of circuit wiring and dielectric breakdown discharge with a simple configuration without requiring a complicated circuit. Can be detected. Since the change in circuit current is detected by using the change in magnetic flux generated in the circuit wiring as a medium, abnormal operation can be detected with high accuracy from abnormal waveforms caused by disconnection discharge of circuit wiring or discharge between high and low voltage parts, etc. It is high, and the occurrence of operation abnormality can be found quickly. In addition, since the change in circuit current is detected indirectly in a non-contact manner with the circuit wiring, it does not affect the circuit conditions of the inverter or load or change the circuit conditions. The current detection unit and the detection signal output unit can be configured without requiring any special components or circuits, regardless of the circuit configuration on the inverter side.
[0120]
(4) In the inverter abnormality detection circuit of the present invention, if the inverter is provided with a control unit that receives a detection signal and stops the inverter operation when the operation is abnormal, the operation can be performed as quickly as possible when the operation is abnormal. Since the inverter can be stopped, the inverter and its load can be protected from the continuation of the abnormal operation, and the safety and reliability of the inverter can be improved.
[0121]
(5) According to the display device of the present invention, when the operation is abnormal, the operation abnormality or the operation stop is displayed, so that the operation abnormality or the inverter operation stop can be easily known from the display, and the protection function is improved and the inverter is improved. Operation reliability can be improved.
[0122]
(6) According to the information processing apparatus of the present invention, by using the abnormality detection circuit of the inverter and the display device, an abnormality such as a disconnection discharge or a dielectric breakdown discharge can be detected, and the operation is stopped based on the detection. Therefore, the continuation of the abnormal state can be avoided, or the operation state can be easily confirmed by the abnormal display or the operation stop display, and the reliability of the information processing apparatus can be further improved.
[0123]
(7) According to the test method or the test apparatus of the present invention, a test is performed by supplying current to a current route including a load to which the AC output of the inverter is supplied, and an abnormality such as a disconnection discharge or a ground fault discharge occurring in the current route is performed. Can be easily detected, a highly reliable test result can be obtained, and the reliability of various products such as an FL tube and a liquid crystal display unit can be improved.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an FL tube lighting device according to an embodiment of a current detection method for an inverter, a current detection circuit thereof, an abnormality detection method thereof, and the abnormality detection circuit of the present invention.
FIG. 2 is a diagram illustrating an example of a current detection unit of the FL tube lighting device.
3A and 3B show operation waveforms of the FL tube lighting device, in which A shows a waveform in a normal operation, and B shows a waveform in an abnormal operation.
FIG. 4 is a circuit diagram showing the FL tube lighting device when the operation is abnormal.
5A and 5B are circuit diagrams showing other parts of the current detection part, wherein FIG. 5A is a circuit diagram showing a case where the primary side of the inverter transformer is used as a current detection part, and FIG. FIG. 9 is a circuit diagram showing the case where the above is set.
6A and 6B show another embodiment of the current detection unit, wherein FIG. 6A is a perspective view showing a case where a core is used, FIG. 6B is a perspective view showing a case where a current detection wire is wound around the core, and FIG. () Is a diagram showing a case where a current detection line is wound around circuit wiring.
FIG. 7 is a diagram illustrating a current detection unit according to another embodiment.
FIG. 8 is a diagram showing a configuration for detecting leakage magnetic flux in a core gap of an inverter transformer.
FIG. 9 is a circuit diagram showing an embodiment of the display device of the present invention.
FIG. 10 is a flowchart illustrating an operation abnormality confirmation process.
11A and 11B show an embodiment of an information processing apparatus according to the present invention, in which FIG. 11A is a perspective view showing a mobile phone using the inverter according to the present invention, and FIG. 11B is a notebook personal computer using the inverter according to the present invention; FIG. 4 is a perspective view showing a computer.
FIG. 12 is a diagram showing an embodiment of the test apparatus of the present invention.
FIG. 13 is a flowchart showing a test procedure.
FIG. 14 is a diagram showing experimental results of the current detection unit according to the present invention.
[Explanation of symbols]
1 FL tube lighting device
2 Inverter
4 FL tube (load)
6. Abnormality detection circuit
14, 16, 52, 54, 70, 72 circuit wiring
20 Inverter control unit (control unit)
22 Inverter transformer
30 Current detector
32 Current change detector
36 Current detection line (detection conductor)
64 LCD
74 core
78 processor
86 Mobile phone (information processing device)
88 Notebook type personal computer (information processing device)
Δφ magnetic flux change
i _d DC input current (circuit current)

Claims (10)

A current detection method for an inverter that converts a DC input to an AC output and supplies the AC output to a load,
An inverter current detection method, wherein a change in the circuit current is detected through a change in magnetic flux due to a change in the circuit current of the inverter caused by discharging. A current detection circuit of an inverter that converts a DC input into an AC output and supplies the AC output to a load,
An inverter current detection circuit, comprising: a current detection unit that detects a change in the circuit current by using a change in magnetic flux due to a change in the circuit current of the inverter caused by the discharge as a medium. The current detector may be configured to detect a change in magnetic flux generated between the circuit wiring or the core gap of the transformer by a detection conductor provided adjacent to a circuit gap of the inverter or a core gap of the transformer. The inverter current detection circuit according to claim 2, wherein A method for detecting an abnormality of an inverter that converts a DC input into an AC output and supplies the AC output to a load,
A change in the circuit current is detected through a magnetic flux change caused by a change in the circuit current of the inverter caused by the discharge, and based on the detection result, whether or not the current route including the load is abnormal is detected. A method for detecting abnormality of an inverter. An abnormality detection circuit for an inverter that converts a DC input into an AC output and supplies the AC output to a load,
A current detection unit that detects a change in the circuit current through a change in magnetic flux due to a change in the circuit current of the inverter caused by the discharge;
A detection signal output unit that outputs a detection signal indicating whether there is an abnormality in the current route including the load, based on a detection result of the current detection unit;
An abnormality detection circuit for an inverter, comprising: The inverter abnormality detection circuit according to claim 5, wherein the inverter includes a control unit that receives the detection signal and stops the inverter operation when the operation is abnormal. A display device, comprising: the inverter current detection circuit according to claim 2 or the inverter abnormality detection circuit according to claim 5, wherein an abnormality or an operation stop of the inverter is displayed when an abnormality occurs. An information processing apparatus comprising the inverter current detection circuit according to claim 2, the inverter abnormality detection circuit according to claim 5, or the display device according to claim 7. A test method using an inverter that converts a DC input into an AC output and supplies the AC output to a load,
Detecting a change in the circuit current through a change in a magnetic flux due to a change in the circuit current of the inverter caused by the discharge, and determining whether there is an abnormality in a current route including the load based on the detection result. A test method characterized by the following. An inverter that converts a DC input into an AC output and supplies the AC output to a load;
A current detection unit that detects a change in the circuit current, through a change in magnetic flux due to a change in the circuit current of the inverter caused by the discharge,
A test apparatus configured to determine whether a current route including the load has an abnormality based on a detection result of the current detection unit.

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